1. Field of the Invention
The present invention relates to an apparatus for enhancing the instructional value of a videotape by superimposing images over one another and by adding visual and/or audio information to a resultant video tape.
2. Discussion of Background
It is said that form is everything in the sport of golfing, and that all will be good if correct form is used in making the golf swing. In analyzing a golfer's golf swing, it is useful to offer critique of the golfer from the side when addressing the ball, from both the side and from the front when the golfer has the golf club at the top of the backswing, and from the side as the golf club impacts the ball.
In a side view of the stance of the golfer addressing the ball, a correct posture may be defined by an angle formed between the club shaft and a line connecting the top of the golfer's shoulder with the club head. The angle should preferably be between 10.degree. and 25.degree., although it depends to some degree upon the length of the club shaft and other variables.
In a side view of the golfer with the club head at the top of the backswing, a correct posture may be defined by a triangle drawn between the golfer's hands (gripped on the club shaft) and the golfer's elbows. The apex of the triangle is formed by the gripped hands, and the base of the triangle extends between the elbows. When correct form is used, the triangle is an equilateral triangle with a horizontal base.
In a front view of the golfer having the club head at the top of the backswing, the golfer's form is correct if a line drawn around the golfer's shoulders forms an ellipse lying horizontally and in parallel with an ellipse formed by a line drawn around the golfer's knees. Preferably, the ellipses align with one another, such that they can be connected by a pair of tangential lines which are parallel to one another, thereby forming a regular cylindrical shape.
In a side view of the golfer during impact of the golf ball, the correct form may be determined by analyzing a first line extending along the club shaft from the club head through the shoulders of the golfer, and a second line connecting the back sirloin and protruding right knee of the golfer. When correct form is used, the lines are substantially parallel to one another, although it is also acceptable if the angle is between about 10.degree. and about 25.degree..
Even when a golfer knows the desired posture at every phase of the swing motion, the golfer is generally unable to properly assess and adjust his or her posture. The underlying reason is that the golfer is unable to see his or her own form. Furthermore, even if the golfer's performance is videotaped and replayed, the golfer may not be able to tell whether or not his/her posture is correct in the video.